Kidney Week

Abstract: TH-PO153

Long-Term Effects of Hypercalcemia in Kidney Transplant Recipients with Persistent Hyperparathyroidism

Session Information

• Bone and Mineral Metabolism: CKD-MBD Updates
  November 02, 2023 | Location: Exhibit Hall, Pennsylvania Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Bone and Mineral Metabolism

• 502 Bone and Mineral Metabolism: Clinical

Authors

• Cojuc, Gabriel, Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Ciudad de Mexico, Ciudad de México, Mexico

Gabriel Cojuc,

• Marino-Vazquez, Lluvia A., Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Ciudad de Mexico, Ciudad de México, Mexico

Lluvia A. Marino-Vazquez,

• Pichardo, Nathalie D., Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Ciudad de Mexico, Ciudad de México, Mexico

Nathalie D. Pichardo,

• Cruz Rivera, Cristino, Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Ciudad de Mexico, Ciudad de México, Mexico

Cristino Cruz Rivera,

• Reza-Albarrán, Alfredo A., Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Ciudad de Mexico, Ciudad de México, Mexico

Alfredo A. Reza-Albarrán,

• Correa-Rotter, Ricardo, Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Ciudad de Mexico, Ciudad de México, Mexico

Ricardo Correa-Rotter,

• Morales-Buenrostro, Luis E., Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Ciudad de Mexico, Ciudad de México, Mexico

Luis E. Morales-Buenrostro,

• Ramirez-Sandoval, Juan Carlos, Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Ciudad de Mexico, Ciudad de México, Mexico

Juan Carlos Ramirez-Sandoval,

Background

Hypercalcemia is prevalent in kidney transplant recipients (KTRs) with hyperparathyroidism. However, its long-term impact on graft function is uncertain.

Methods

Prospective cohort study investigating adverse graft outcomes associated with persistent hypercalcemia (free calcium >5.2 mg/dL in ≥80% of measures) and inappropriately elevated PTH (>30 pg/mL) in KTRs. Asymptomatic mild hypercalcemia was observed unless complications developed.

Results

We included 385 KTRs. During a 4-year (IQR 1-8.2) median follow-up, 62% of KTRs presented persistent hypercalcemia. Compared to KTRs without hypercalcemia, there were no significant differences in graft dysfunction (10% Vs. 12%,p=0.61), symptomatic urolithiasis (5% Vs. 3%, p=0.43), biopsy-proven calcium deposits (6% Vs. 5%, p=1.0), fractures (6% Vs. 4%, p=0.64), and a composite outcome of urolithiasis, calcium deposits, fractures, and parathyroidectomy indication (10% Vs. 5%, p=0.55) in subjects with persistent hypercalcemia. In a subset of 76 KTRs, those with persistent hypercalcemia had higher urinary calcium (median 84 [43-170] Vs. 38 [24-64] mg/day,p=0.03) and iFGF23 (median 36 [24-54] Vs. 27 [19-40] pg/mL,p=0.04) levels, and lower 25D levels (11.3±1.2 Vs. 16.3±1.4 ng/mL,p<0.001). An iPTH level <300 pg/mL was associated with a reduced risk of post-transplant hypercalcemia in a multivariate analysis (OR 0.51, 95% CI 0.32-0.80).

Conclusion

Long-term persistent mild hypercalcemia, with inappropriately elevated iPTH, was frequent in KTRs after transplantation. This condition closely resembled a mild form of primary hyperparathyroidism, with hypophosphatemia and hypovitaminosis D as well as increased urinary calcium and iFGF23 levels. Despite these symptoms, the risk of adverse graft outcomes was low.

Outcomes associated with hypercalcemia